A lower bound of the crossing number of composite knots

Let $c(K)$ denote the crossing number of a knot K and let K₁# K₂ denote the connected sum of two oriented knots K₁ and K₂. It is a very old unsolved question that whether c(K₁# K₂)=c(K₁)+c(K₂). In this paper we show that c(K₁# K₂)> (c(K₁)+c(K₂))/16.